I have an Arduino Nano, a 9-volt battery, and a motor. Unfortunately, I do not have the specs of the motor (it’s lodged inside a furby and that’s where I’d like it to stay). The furby had 4 AA batteries, totaling 6v, so that is what I suspected the motor to be rated for.
To confirm this hypothesis, I tried running the motor, first via a PWM pin on the Arduino, which cause sound but no movement, and then with the 9v battery directly, which did run the motor.
The thing is, I really don’t want to stress this motor too much. My understanding is that the motor will draw whatever amperage it needs so long as the proper voltage is supplied (unless the power source isn’t capable of doing so, like the 40mA limit in an Arduino pin), so I want to find a way to get my 9v battery down to 6v or my Arduino up to 6v.
I also have ordered an L298 (an h-bridge integrated circuit) to control direction.
I’ve done some research, and so far I’ve found three options:
Voltage divider. This is a really simple circuit to reduce the 9v to 6v fairly easily. I have, however, been informed that it is highly inefficient in this application (though in all honesty I have very little idea as to what that means).
DC-DC step-down buck converter. This is a much more efficient, much more complicated circuit that I do not fully understand, but they’re sold online, so I could probably use one. This would also take the 9v and reduce it to 6v.
Step-up boost converter. This would increase my 5v Arduino output to 6v, bypassing the battery completely, which would be ideal, but I don’t know if the current would be sufficient, nor do I understand how it works.
If you have any insight as to which of these would be preferable (or feasible), please advise. Or, if you have any alternatives that you think would be better, please tell me.
The much more serious problem is stressing the Arduino, which cannot directly control or power any motors. You need a motor driver of some sort, and a separate power supply. There is one of each built into the Furby. People have hacked them, and posted the info on the web.
Yes, an H-bridge allows bidirectional control. A single transistor will work for unidirectional control. One or the other is already built into the Furby.
Looking into this. I also have an audio amplifier that I had been running off of the 9v battery. Would using 4 double a's reduce its volume significantly?
Motor ratings are nominal. A toy motor will run on anything between 1.5 and 12V or more (if the power supply can supply the required current) but the motor lifetime goes down as the voltage increases.
A 9V PP3 smoke alarm battery can't provide enough current to run a toy motor for a useful length of time.
Alright, will try this. It seems like an ideal solution would be to have the amplifier and the motor running on the same 4 AA batteries. Thank you all for your help! I love this community!